Natural products, for example, the aromatic substances, exert a very important role in chemical, food and pharmaceutical industries. The said natural aromatic substances may be obtained from animals or plants: those obtained from animals include musk and ambergris while those obtained from plants are more diverse—essential oils, balsams, oleoresins are the most common ones (there are also many artificial aromatic substances, including alcohols and esters). In order to utilize natural substances in chemical, petrochemical, food and pharmaceutical industries, rectification devices are indispensble. The traditional rectification process can be divided into two models: the batch rectification (see FIG. 2) and the continuous rectification (see FIG. 3); the system designed for the batch rectification process includes a batch rectification tower, a heating device and a condensation-recirculation device. Its basic operating procedure goes as follow: feeding all the raw material at once into the tower bottom 29 for heating and evaporation; the gas generated therein emits up through the rectification tower 25 into the condenser 26, wherein it is condensed into liquid; part of the condensed liquid flows back into the rectification tower and is heated again in the tower bottom, and the rest of it is discharged out; after a certain period of heating, the light component of the raw material in the tower bottom is completely separated out, then all the material in the tower bottom is discharged at once without adding any new raw material. Compared with the batch rectification device, the continuous rectification device is installed with a feeding device 40 and a reboiler 35. Its basic operating procedure goes as follow: starting up the whole device and feeding the raw material into the bottom of the rectification tower; heating the material when the liquid reaches a certain level; all the condensed liquid obtained from the tower top flows back and no new raw material is added during this full recirculation stage; subsequently, only part of the condensed liquid channeled out from the condenser 34 flows back into the rectification tower while the rest is discharged out; in addition, part of the liquid flowing into the tower bottom is discharged out as well, only the rest of it is channeled into the reboiler 35 for further heating and evaporation; the gas generated therein flows into the rectification tower 33 and emits upwards in the rectification tower; meanwhile, the raw material should be added continuously to maintain the liquid in the tower bottom at a constant level. Currently, most existing rectification processes adopt the two procedures mentioned above. However, the said procedures are characteristic of long time of heating for the raw material; when they are adopted for separating natural substances, most of which are thermosensitive, the high temperature and long-time heating used in these procedures will lead to such thermosensitization reactions as polymerization, dehydration, oxidation and decomposition, which consequently result in coke deposition, carbon deposition, coloration, discoloration, and damages to aromatic properties of the natural substances; therefore, these reactions cause not only damage to the product quality, but also waste of precious natural resources.